Conventional automated optical inspection (AOI), such as for packaging of semiconductor devices that includes fixed or constant features and does not include unit specific features of unit specific, is known in the art, and has been conventionally accomplished by comparing a reference image or “golden image” with an image captured during visual inspection of the conventional semiconductor device. The golden image is constructed by combining multiple images of known good parts. The combination of multiple images effectively provides an average or idealized part or package that averages out defects, aberrations, variations, or “noise” that is present on even acceptable, functional, or good parts.
An image captured by visual inspection is simply a visual or graphical representation, like a photograph, that shows a package or package component as it actually exists or was made, which can differ from its original design or intended structure. After having both a golden image and an actual image captured during visual inspection, the image or images captured of various parts of semiconductor packages are each compared, in turn, against the idealized or standardized golden image. In some instances, the comparison is done by subtraction so that the golden image and the image captured by visual inspection are compared pixel-by-pixel to produce a resulting image that shows or indicates differences between the golden image and the image captured by visual inspection. Results of the comparison can be processed with threshold filters and spatial filters to find defects in the visually inspected product. Defective products can be identified and dealt with accordingly.